Index: wp-admin/includes/ajax-actions.php
===================================================================
--- wp-admin/includes/ajax-actions.php	(revision 38094)
+++ wp-admin/includes/ajax-actions.php	(working copy)
@@ -3678,6 +3678,13 @@
 
 	wp_update_plugins();
 
+	// save whether the plugin is active or not
+	$plugin_active = is_plugin_active( $plugin );
+	$plugin_network_active = is_plugin_active_for_network( $plugin );
+	
+	// silently deactivates the plugin prior to upgrading it
+	add_filter('upgrader_pre_install', array($upgrader, 'deactivate_plugin_before_upgrade'), 10, 2);
+
 	$skin     = new Automatic_Upgrader_Skin();
 	$upgrader = new Plugin_Upgrader( $skin );
 	$result   = $upgrader->bulk_upgrade( array( $plugin ) );
@@ -3691,6 +3698,14 @@
 	}
 
 	if ( is_array( $result ) && ! empty( $result[ $plugin ] ) ) {
+	
+		// Silently reactivate the plugin afterwards
+		if ( !is_wp_error( $result ) && $plugin_active ) {
+			// plugin_info() is called in case the main plugin file name changed
+			$plugin = $upgrader->plugin_info();
+			activate_plugin( $plugin, '', $plugin_network_active, true );
+		}
+		
 		$plugin_update_data = current( $result );
 
 		/*